Polymer Plastic Front Plate And Method For Manufacturing The Same

ABSTRACT

A polymer plastic front plate comprises: a plastic substrate and a hard coating layer formed on an adhesion surface of the plastic substrate. The hard coating layer comprises: organic-inorganic hybrid UV oligomer, high Tg UV resin additive, a plurality of dispersed flaky nano inorganic material, and photo initiator, so as to form a gas barrier hard coating layer with high surface dyne value (&gt;44 dyne) on the adhesion surface of the plastic substrate. It not only has good ink printability and OCA adhesiveness, but also inhibits the diffusion of fugitive gas from polymer plastic front plates during high-temperature, high-temperature and high-humidity, high-low temperature thermal shocks and other harsh automotive industry environmental tests. The gas can be avoided from entering the OCA layer, thereby solving the problems of bubbles and delamination after the environmental tests are performed.

BACKGROUND OF INVENTION 1. Field of the Invention

The invention refers to a polymer plastic front plate and a method formanufacturing the same, especially refers to a polymer plastic frontplate which is suitable for bonding on the surface of automotive touchpanels.

2. Description of the Prior Art

Generally speaking, a touch panel on a touch-sensitive electronic devicefor a car is usually fitted with a front panel, not only because thefront panel can protect the touch panel from scratches, but also becausethe front panel can also be printed with specific patterns or text formarking a specific touch area on the touch panel so as to improve theconvenience of the user to operate the touch panel.

Please refer to FIG. 1, which is a schematic diagram of a typicalexample of a conventional technology, in which a front panel is attachedto the front surface of a touch panel. The front panel 10 currently usedfor laminating on a touch panel is usually composed of a polymer plasticmaterial, which comprises a plastic substrate 11 primary made ofpolymethyl methacrylate (PMMA) or polycarbonate (PC), a protective layer12 disposed on an operation surface (outer surface) of the plasticsubstrate 11, and a hard coating layer 13 disposed on a bonding surface(inner surface) of the plastic substrate 11. The protective layer 12 andthe hard coating layer 13 are applied to two different surfaces of theplastic substrate 11 by a hard coating (HC) technology. Currently,common HC materials include UV-curable multifunctional high surfacetension oligomers (Oligomer) or high surface tension monomerformulations, which can be formed as a thin film on the surface of theplastic substrate 11 for increasing the hardness thereof, so as toprovide a scratch-resistant effect. HC technology is mainly used on thesurface of soft substrates, such as PC or PMMA plastic substrates 11.These kinds of plastic substrate 11 are relatively soft. After thesurface is hardened by hard coating, the hardness can be as hard asglass, which is easy to be wiped clean and uneasy to be scratched. Inaddition, an ink layer 21 of a specific pattern or text can be printedon the surface of the hard coating layer 13 formed on the bondingsurface of the plastic substrate 11 by means of ink printing; afterthat, an optical clear adhesive 22 (OCA) is applied to the hard coatinglayer 13 formed on the bonding surface of the plastic substrate 11, andthen the front panel 10 is attached to the touch panel 23, letting thehard coating layer 13 and the ink layer 21 to be sandwiched between theplastic substrate 11 and the touch panel 23 and are adhesively bonded bythe optical clear adhesive 22.

The composition of HC materials of the hard coating layer 13 formed onthe bonding surface of the conventional plastic substrate 11 is a highlycross-linked ultraviolet light curing typed (UV-curable) resinformulation, for example, a multifunctional high surface tensionoligomer formulation or a high surface tension monomer formulation. Thehighly cross-linked UV-curable resin formulation is coated on the OCAbonding surface of PC or PMMA plastic substrate 11, which not only canprovide ink-printability and scratch resistance abilities to the bondingsurface of the plastic substrate 11, but also can avoid surface damagecaused by ink printing process. Although the composition of HC materialsof the hard coating layer 13 of the conventional plastic substrate 11has a high surface dyne value (>38 dyne), which is capable of inkprinting and suitable for optical clear adhesive 22 (OCA) bonding, andhas good adhesion with the optical clear adhesive 22 (OCA); however,because the ordinary multifunctional high surface tension oligomer andhigh surface tension monomer formula are not effective in blocking gasdiffusion, therefore, it is still impossible to pass the environmentaltests of harsh high-temperature, high-temperature and high-humidity, andhigh-low temperature (hot and cold) thermal shocks for the front panel10 of the touch panel of vehicle electronic device in the automotiveindustry. Thus, the front panel 10 will suffer problems such asoutgassing, delay bubbles caused by moisture intrusion, and delaminationafter the environmental tests.

In the embodiments described below, since most of the elements are thesame or similar to the typical example shown in FIG. 1, the same orsimilar elements will be given with the same name and numeral directly,and will not be described in detail.

Please refer to FIG. 2, which is a schematic diagram of another typicalexample of a conventional front panel. In order to improve the effectfor blocking the diffusion of gas, one approach is to additionallyprovide a “single-layer” continuous gas barrier layer 14 on the hardcoating layer 13 formed on the bonding surface of the front panel 10 a.The material of the single-layer continuous gas barrier layer 14 can bean air-impermeable material such as alumina, and is completely coveringthe entire surface of the hard coating layer 13. The advantage of thisapproach is that the continuity of the gas barrier layer 14 and theoptical clear adhesive 22 (OCA) is good, and the initial gas barriereffect is excellent. However, since the continuous gas barrier layer 14is subjected to the environmental tests with high-low temperature (hotand cold) thermal shocks, many micro or nano cracks will be generated,and thus, the gas barrier effect becomes poor after the environmentaltests; in addition, the continuous gas barrier layer 14 must be formedby using vacuum coating process, the costs is high, and the productionefficiency is low; furthermore, the printability of ink of thecontinuous gas barrier layer 14 is poor (poor adhesion between theinorganic layer material and the ink); therefore, such approach is not agood solution.

Please refer to FIG. 3, which is a schematic diagram of a furthertypical example of a conventional front panel. Another approach of theprior art is to add a plurality of dispersed spherical nano gas barrierparticles 212 into the hard coating layer 210 formed on the bondingsurface of the front panel 20. These spherical nano gas barrierparticles 212 can be made of air-impermeable material such as alumina,and are discontinuously dispersed in the highly cross-linked UV-curableresin material 211 included in the entire hard coating layer 210, inorder to form a discontinuous gas barrier structure in the hard layer210. The advantages of this approach are that the adhesion between thehard coating layer 210 and the optical clear adhesive (OCA) is good, andthe printability of ink is also good; in addition, the material ofspherical nano gas barrier particles 212 is also easy to get. However,because the gas barrier structure included in the hard coating layer 210is discontinuous, there are many gaps between these spherical nano gasbarrier particles 212, therefore the initial gas barrier effect forblocking the gas diffusion is not good, and the effect for blocking thegas diffusion after the environmental test is also poor, and thus leavesa room for further improvements.

SUMMARY OF THE INVENTION

The primary objective of the invention is to provide a polymer plasticfront plate suitable for bonding on the surface of automotive touchpanels, which can form a gas barrier hard coating layer with highsurface dyne value (>44 dyne) on the adhesion surface of the plasticsubstrate. It not only has good ink printability and OCA adhesiveness,but also inhibits the diffusion of fugitive gas from polymer plasticfront plates during high-temperature, high-temperature andhigh-humidity, high-low temperature (hot and cold) thermal shocks andother harsh automotive industry environmental tests. The gas can beavoided from entering the OCA layer, thereby solving the problems ofbubbles and delamination after the environmental tests are performed.

Another objective of the invention is to provide a method formanufacturing a polymer plastic front plate suitable for bonding on thesurface of automotive touch panels, which can apply a hard coating layeron the bonding surface of the plastic substrate by using a hard coating(HC) technology. Wherein, the hard coating layer contains a plurality ofdispersed nano-scale flaky inorganic substances arranged in a randomlydistributed horizontal direction in the hard coating layer, so as toform a discontinuously layered dispersed gas barrier layer in the hardcoating layer. Not only can provide good gas barrier effect but also canprevent cracks from happening.

In order to achieve the aforementioned objectives, the inventionprovides a polymer plastic front plate which comprises: a plasticsubstrate having an operation surface and a bonding surface, aprotective layer furnished on the operation surface, and a hard coatinglayer furnished on the bonding surface; wherein the hard coating layercomprises: a first weight percentage of organic-inorganic hybridUV-curable oligomer, a second weight percentage of UV-curable resinadditives with high glass transition temperature (Tg) value, a pluralityof dispersed nano-scale flaky inorganic substances, and a photoinitiator; wherein, the plurality of dispersed nano-scale flakyinorganic substances are arranged in a randomly distributed horizontaldirection in the hard coating layer to form a discontinuously layereddispersed gas barrier layer in the hard coating layer.

In a preferred embodiment, the organic-inorganic hybrid UV-curableoligomer includes a polyurethane resin and a sol-gel silica hybridmixture.

In a preferred embodiment, the glass transition temperature (Tg) valueof the UV-curable resin additives is not less than 120° C. ; inaddition, the UV-curable resin additives contain at least one of thefollowing: UV-curable oligomer with high glass transition temperature(high Tg UV oligomer) and UV-curable monomer with high glass transitiontemperature (high Tg UV monomer).

In a preferred embodiment, the UV-curable oligomer with high glasstransition temperature is polyurethane acrylate, which has a glasstransition temperature (Tg) value not less than 120° C.; in addition,the UV-curable monomer with high glass transition temperature isTris(2-hydroxy ethyl) isocyanuratetriacrylate (THEICTA), which has aglass transition temperature (Tg) value not less than 240° C.

In a preferred embodiment, the nano-scale flaky inorganic substances arecomposed of at least one of the following materials: SiO₂, Al₂O₃, Si₃N₄,SiO_(x)N_(y), and AlO_(x)N_(y).

In a preferred embodiment, each of the nano-scale flaky inorganicsubstances has a thickness (t), a longitudinal width (w1) and a lateralwidth (w2); wherein, the measuring directions of the thickness (t), thelongitudinal width (w1) and the lateral width (w2) are perpendicular toeach other, and w1≥w2≥t; wherein, the thickness (t) is between 0.1 nmand 50 nm, the longitudinal width (w1) is between 100 nm and 1000 nm,and the ratio of the lateral width to the longitudinal width (w2/w1) isbetween 0.01 and 1.

In a preferred embodiment, 10 nm≤t≤30 nm, 300 nm≤w1≤800 nm, and0.1≤(w2/w1)≤1.

In a preferred embodiment, the value of the first weight percentage isranged between 50% and 70%, the value of the second weight percentage isranged between 30% and 50%, and the value of the weight percentage ofthe nano-scale flaky inorganic substances in the hard coating layer isbetween 5% and 15%.

In a preferred embodiment, the plastic substrate is one of thefollowing: polymethyl methacrylate (PMMA) plate, polycarbonate (PC)plate, PMMA/PC double-layer composite plate, and PMMA/PC/PMMAthree-layer composite plate; in addition, the surface of the hardcoating layer can be applied with an ink layer and an optical clearadhesive (OCA) layer for attaching to the surface of the touch panel.

In order to achieve the aforementioned objectives, the inventionprovides a method for manufacturing a polymer plastic front plate,comprising: Step (A): providing a plastic substrate and a coatingmaterial;

the plastic substrate having a bonding surface; said coating materialincluding: a first weight percentage of organic-inorganic hybridUV-curable oligomer, a second weight percentage of UV-curable resinadditives with high glass transition temperature (Tg) value, a pluralityof dispersed nano-scale flaky inorganic substances, and a photoinitiator; Step (B): applying the coating material onto the bondingsurface of the plastic substrate; and Step (C): curing the coatingmaterial to form a hard coating layer on the bonding surface of theplastic substrate; wherein, during the curing process, the plurality ofdispersed nano-scale flaky inorganic substances will be affected by thegravity and hydrodynamics, and randomly dispersed and arranged along ahorizontal direction in a parallel manner within the hard coating layer,such that the plurality of dispersed nano-scale flaky inorganicsubstances can form a discontinuously layered dispersed gas barrierlayer in the hard coating layer.

In a preferred embodiment, the process for providing the coatingmaterial described in Step (A) comprises the following steps: Step (A1):forming an inorganic layer on a carrier plate; Step (A2): detaching andbraking the inorganic layer into a plurality of tiny inorganicfragments; Step (A3): smoothing and dispersing the plurality of tinyinorganic fragments in order to transform the plurality of tinyinorganic fragments into the plurality of dispersed nano-scale flakyinorganic substances; and Step (A4): adding and mixing the plurality ofdispersed nano-scale flaky inorganic substances into a solution of theorganic-inorganic hybrid UV-curable oligomer, the UV-curable resinadditive and the photo initiator to form the coating material.

In a preferred embodiment, in Step (A1), the carrier plate is a glasscarrier plate, and a release film is provided on a surface of the glasscarrier plate; an inorganic material is plated on the release film by avacuum sputtering process in order to form a whole piece of theinorganic layer on the surface of the release film; in Step (A2), theinorganic layer is broken by shaking, vibrating or striking the carrierplate, such that the broken inorganic layer can be detached from therelease film of the carrier plate and be broken into the plurality oftiny inorganic fragments; in Step (A3), the plurality of tiny inorganicfragments are mixed and stirred by a nano dispersion equipment, so thatthe plurality of tiny inorganic fragments can collide with each other togradually smooth their sharp edges and also disperse them evenly andindividually, so as to form the plurality of dispersed nano-scale flakyinorganic substances.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be specified with reference to itspreferred embodiment illustrated in the drawings, in which:

FIG. 1 is a schematic diagram of a typical example of a conventionalfront panel;

FIG. 2 is a schematic diagram of another typical example of aconventional front panel;

FIG. 3 is a schematic diagram of a further typical example of aconventional front panel;

FIG. 4 is a schematic diagram of a preferred embodiment of a polymerplastic front panel suitable for a sunroof of vehicle according to thepresent invention;

FIG. 5 is a flow chart showing an embodiment of the method formanufacturing the polymer plastic front plate in accordance with theinvention;

FIG. 6 is a flowchart of an embodiment of the process for providing thecoating material of the hard coating layer in accordance with the methodfor manufacturing the polymer plastic front panel of the presentinvention;

FIGS. 7A to 7C respectively are some schematic diagrams of severaldifferent steps of the flowchart shown in FIG. 6, in accordance with themethod for manufacturing the polymer plastic front panel of the presentinvention;

FIG. 8A to FIG. 8C respectively are the schematic diagrams of the hardcoating layer at some different stages during the curing process ofcoating material in accordance with the manufacturing method of thepolymer plastic front panel of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The polymer plastic front plate of the invention is suitable for bondingon the surface of automotive touch panels. By means of the addition oforganic-inorganic high Glass Transition Temperature (Tg) UV oligomersand nano-scale flake-like inorganic oxides, a gas barrier hard coatinglayer with high surface dyne value (>44 dyne) can be formed on theadhesion surface of the plastic substrate. It not only has good inkprintability and OCA adhesiveness, but also inhibits the diffusion offugitive gas from polymer plastic front plates during high-temperature,high-temperature and high-humidity, high-low temperature (hot and cold)thermal shocks and other harsh automotive industry environmental tests,which is due to the fact that these nano-scale flaky inorganic oxidescan form a discontinuously layered dispersed gas barrier layer in thehard coating layer. The gas can be avoided from entering the OCA layer,thereby solving the problems of bubbles and delamination after theenvironmental tests are performed.

In order to more clearly describe the structure of the polymer plasticfront plate and method for manufacturing the same, detailed descriptionswill be provided below with reference to the drawings.

Please refer to FIG. 4, which is a schematic diagram of a preferredembodiment of a polymer plastic front panel suitable for a sunroof ofvehicle according to the present invention. The polymer plastic frontpanel 30 of the present invention can be bonded on a touch panel (notshown in the figure) of a touch-sensitive typed electronic device for avehicle by using optical clear adhesive (not shown in the figure), whichcomprises: a plastic substrate 11, a protective layer 12 and a hardcoating layer 31. The polymer plastic front panel 30 of the presentinvention can be made into a polymer plastic sheet with high hardness,high wear resistance, high impact resistance, high flexibility, andextremely low gas transmission rate, or be used to replace traditionaltempered glass as the cover material of touch panel, which isparticularly suitable for cover materials of automotive touch panels inorder to meet the harsh high-temperature or high-temperaturehigh-humidity environmental testing specifications.

In in embodiment, the plastic substrate 11 is one of the following:polymethyl methacrylate (PMMA) plate, polycarbonate (PC) plate, PMMA/PCdouble-layer composite plate, PMMA/PC/PMMA three-layer composite plate,or other kind of single-layer or multi-layer co-extruded plate made ofpolymer materials. When the plastic substrate is a multilayer plate,polycarbonate (PC) can be used as the material of the main-layer with athickness accounting for 60%-99.99% of the total thickness of theplastic substrate. In the other hand, each of the sub-layers located oneither one side or two opposite (outer and inner) sides of themain-layer may have a thickness accounting for 0.01%-40% of the totalthickness of the plastic substrate, and the material of the sub-layermay be chosen from one of the following: PMMA, Modified PMMA, ModifiedPC, PMMI, PET, PEN, PES, PI, and etc. The plastic substrate 11 has acorresponding operation surface (outer surface) and a bonding surface(inner surface); in which, the side of the operation surface is for theuser to touch and operate the touch panel, while the side of the bondingsurface is for printing an ink layer and for applying an optical clearadhesive in order to bond to the touch panel. The protective layer 12 isfurnished on the operation surface (outer surface) of the plasticsubstrate 11, while the hard coating layer 31 is furnished on thebonding surface (inner surface) of the plastic substrate 11. Theprotective layer 12 and the hard coating layer 31 are respectivelyapplied to the operation surface (outer surface) and the bonding surface(inner surface) of the plastic substrate 11 by a hard coating (HC)technology. As shown in FIG. 4, the surface of the hard coating layer 31of the invention can also be applied with both an ink layer and anoptical clear adhesive (OCA) layer for attaching to the surface of thetouch panel. In this embodiment, the thickness of the plastic substrate11 is between 100 μm and 1000 μm.

In the present invention, the thickness of the hard coating layer 31 canbe between 0.1 μm and 100 μm, and is better between 1 μm and 50 μm, andis best between 5 μm and 30 μm. In this embodiment, the hard coatinglayer 31 is composed of a mixture of: a coating material 32, a pluralityof dispersed nano-scale flaky inorganic substances 33, and a photoinitiator; wherein, the resin formulation of the coating material 32includes a first weight percentage of organic-inorganic hybridUV-curable oligomer, and a second weight percentage of UV-curable resinadditives with high glass transition temperature (Tg) value. Inaddition, the plurality of dispersed nano-scale flaky inorganicsubstances 33 are arranged in a randomly distributed horizontaldirection in the coating material 32 of the hard coating layer 31, so asto form a discontinuously layered dispersed gas barrier layer in thehard coating layer 31. These randomly and horizontally distributednano-scale flaky inorganic substances 33 not only can provide good gasbarrier effect but also can prevent cracks from happening in the hardcoating layer 31. In this embodiment, the organic-inorganic hybridUV-curable oligomer includes a polyurethane resin and a sol-gel silicahybrid mixture. The glass transition temperature (Tg) value of theUV-curable resin additives is not less than 120; in addition, theUV-curable resin additives contain at least one of the following:UV-curable oligomer with high glass transition temperature (high Tg UVoligomer) and/or UV-curable monomer with high glass transitiontemperature (high Tg UV monomer). In a preferred embodiment of theinvention, the UV-curable oligomer with high glass transitiontemperature is polyurethane acrylate, which has a glass transitiontemperature (Tg) value not less than 120° C. The UV-curable monomer withhigh glass transition temperature is Tris(2-hydroxy ethyl)isocyanuratetriacrylate (THEICTA), which has a glass transitiontemperature (Tg) value not less than 240° C. The nano-scale flakyinorganic substances 33 are composed of at least one of the followingmaterials: SiO₂, Al₂O₃, Si₃N₄, SiO_(x)N_(y), and/or AlO_(x)N_(y). Inthis embodiment, the value of the first weight percentage is rangedbetween 50% and 70%, the value of the second weight percentage is rangedbetween 30% and 50%, and the value of the weight percentage of thenano-scale flaky inorganic substances 33 in the hard coating layer isbetween 5% and 15%.

The organic-inorganic hybrid UV oligomer contained in the hard coatinglayer 31 can provide the optical clear adhesive (OCA) bonding surface ofthe polymer plastic front panel 30 with high hardness and high wearresistance. In addition, the high Tg UV oligomer (≥120° C.) and/or highTg UV monomer (≥240° C.) contained in the hard coating layer 31 canprovide the optical clear adhesive (OCA) bonding surface of the polymerplastic front panel 30 with high impact resistance, high flexibility,and stability at high temperatures, which can reduce the air chamberspace during the high-temperature and high-humidity environmental tests,reduce polymer pores, and thus reduce gas permeability. The reason whythe polymer plastic front panel 30 of the present invention contains amaterial with a high Tg (above 120° C.) is that, when the temperature ofworking environment of the polymer plastic front panel 30 is close tothe Tg point (glass transition temperature) of the polymer material, theporosity of the polymer material will increase, which will cause watervapor to enter. The highest testing temperature of the environmentaltests for vehicles is 90° C. If the Tg of the material is lower than orclose to 90° C., when the working temperature of 90° C. is reached, thepolymer segment will soften and the porosity will increase, which willcause water vapor to penetrate more easily and fail to provide theeffect of blocking water vapor. This problem can be avoided as long asthe Tg of the resin formulation material contained in the coatingmaterial 32 of the hard coating layer 31 is 120° C. or above. Moreover,the randomly and horizontally distributed nano-scale flaky inorganicsubstances 33 contained in the coating material 32 of the hard coatinglayer 31 can provide the polymer plastic front panel 30 with a very lowgas transmission rate, and can also maintain high transparency and lowhaze. Because these nano-scale flaky inorganic substances 33 can form adiscontinuously layered dispersed gas barrier layer in the hard coatinglayer 31, which inhibits the diffusion of fugitive gas from the polymerplastic front plate during the high-temperature, high-temperature andhigh-humidity, high-low temperature (hot and cold) thermal shocks andother harsh automotive industry environmental tests, prevents the gasfrom entering the OCA layer, solves the problems of bubbles anddelamination after the environmental tests, and thereby indeedeffectively improves the various shortcomings of the aforementionedconventional techniques.

Please refer to FIG. 5, which is a flow chart showing an embodiment ofthe method for manufacturing the polymer plastic front plate inaccordance with the invention. The method for manufacturing the polymerplastic front plate of the invention comprises the following steps.

Step 51: providing a plastic substrate and a coating material of hardcoating layer. Like the embodiment shown in FIG. 4, the plasticsubstrate of the polymer plastic front plate of the invention has abonding surface and an operation surface. The coating material of thehard coating layer is a paint-like liquid mixture including: a firstweight percentage of organic-inorganic hybrid UV-curable oligomer, asecond weight percentage of UV-curable resin additives with high glasstransition temperature (Tg) value, a plurality of dispersed nano-scaleflaky inorganic substances, a photo initiator, and volatile solvents. Inone embodiment, a protective layer has been formed on the operationsurface of the plastic substrate in advance before performing thefollowing Step 52. However, in another embodiment, there is noprotective layer being formed on the plastic substrate when performingthe Step 52; in contrary, such protective layer is formed on theoperation surface of the plastic substrate after the Step 52 has beencompleted.

Step 52: applying the paint-like liquid coating material of the hardcoating layer onto the entire bonding surface of the plastic substrateby using a hard coating technology.

Step 53: curing the coating material to form the hard coating layer onthe bonding surface of the plastic substrate. In the curing process, thevolatile solvent contained in the coating material is volatilized by abaking or far-infrared (IR) irradiating process, and theorganic-inorganic hybrid UV-curable oligomer and the UV-curable resinadditive contained in the coating material is hardened by an irradiatingprocess of ultraviolet (UV) light with a specific wavelength. Wherein,during the curing process, as the solvent slowly evaporates, theplurality of dispersed nano-scale flaky inorganic substances will beaffected by the gravity and hydrodynamics, and thus randomly dispersedand arranged along a horizontal direction in a parallel manner withinthe hard coating layer, such that the plurality of dispersed nano-scaleflaky inorganic substances can form a discontinuously layered dispersedgas barrier layer in the hard coating layer after the curing process iscompleted. Thereby, a hard coating layer including a discontinuouslylayered dispersed gas barrier layer composed of the plurality ofdispersed nano-scale flaky inorganic substances can be formed on thebonding surface of the plastic substrate.

Please refer to FIG. 6 and FIGS. 7A to 7C, which respectively are theflowchart of an embodiment of the process for providing the coatingmaterial of the hard coating layer, and some schematic diagrams ofseveral different steps thereof, in accordance with the method formanufacturing the polymer plastic front panel of the present invention.In the embodiment shown in FIG. 6, the process for providing the coatingmaterial of the hard coating layer comprises the following steps.

Step 511: forming an inorganic layer 62 on a carrier plate 61. As shownin FIG. 7A, in a preferred embodiment of the invention, the carrierplate 61 is a glass carrier plate 61, and a release film 611 is providedon a surface of the glass carrier plate 61. An inorganic material isplated on the release film 611 by a vacuum sputtering process in orderto form a whole piece of the inorganic layer 62 on the surface of therelease film 611. Wherein, the material of the inorganic materialcomprises one of the following: silicon dioxide (SiO₂), aluminum oxide(Al₂O₃), silicon nitride (Si₃N₄), silicon oxynitride (SiO_(x)N_(y)), andaluminum oxynitride (AlO_(x)N_(y)). In this embodiment, the inorganicmaterial is preferably made of aluminum oxide (Al₂O₃).

Step 512: detaching and braking the inorganic layer 62 into a pluralityof tiny inorganic fragments 621. As shown in FIG. 7B, the entireinorganic layer 62 is broken by shaking, vibrating or striking thecarrier plate 61, such that the broken inorganic layer 62 can bedetached from the release film 611 of the carrier plate 61, and thereleased inorganic layer 62 can be broken into the plurality of tinyinorganic fragments 621. In this step, the plurality of the tinyinorganic fragments 621 obtained are irregular in shape and have sharpedges, but the size of each tiny inorganic fragment 621 does not differmuch.

Step 513: smoothing and dispersing the plurality of tiny inorganicfragments 621 in order to transform the plurality of tiny inorganicfragments 621 into the plurality of dispersed nano-scale flaky inorganicsubstances 622. As shown in FIG. 7B, in this step, the plurality of tinyinorganic fragments 621 are mixed and stirred by a nano dispersionequipment 63, so that the plurality of tiny inorganic fragments 621 willcollide with each other to gradually smooth their sharp edges and alsodisperse them evenly and individually, so as to form the plurality ofdispersed nano-scale flaky inorganic substances 622. As shown in FIG.7C, after the smoothing and dispersing process of the tiny inorganicfragments 621 described in Step 513 is completed, each of the nano-scaleflaky inorganic substances 622 will have a thickness (t), a longitudinalwidth (w1) and a lateral width (w2); wherein, the measuring directionsof the thickness (t), the longitudinal width (w1) and the lateral width(w2) are perpendicular to each other, and w1≥w2≥t. In which, thethickness (t) is between 0.1 nm and 50 nm, the longitudinal width (w1)is between 100 nm and 1000 nm, and the ratio of the lateral width to thelongitudinal width (w2/w1) is between 0.01 and 1. In the presentinvention, a best effect can be achieved when 10 nm≤t≤30 nm, 300nm≤w1≤800 nm, and 0.1≤(w2/w1)≤1.

Step 514: adding and mixing the plurality of dispersed nano-scale flakyinorganic substances 622 into the solution of organic-inorganic hybridUV-curable oligomer, the UV-curable resin additive, the photo initiator,and the volatile solvent to form the coating material of the hardcoating layer. In this embodiment, the organic-inorganic hybridUV-curable oligomer comprises polyurethane resin and sal-gel silicahybrid mixture. The glass transition temperature (Tg) value of theUV-curable resin additive is not less than 120° C., in addition, theUV-curable resin additive comprises at least one of the following: highTg UV-curable oligomer or high Tg UV-curable monomer. In a preferredembodiment of the invention, the high Tg UV-curable oligomer ispolyurethane acrylate, which has a Tg value not less than 120° C. Thehigh Tg UV-curable monomer is Tris(2-hydroxy ethyl)isocyanuratetriacrylate (THEICTA), which has a Tg value not less than240° C. The weight percentage of the organic-inorganic hybrid UVoligomer in the coating material is ranged between 50% and 70%, theweight percentage of the high Tg UV-curable resin additive is rangedbetween 30% and 50%, the weight percentage of the nano-scale flakyinorganic substances in the coating material of the hard coating layeris between 5% and 15%, and the weight percentage of the photo initiatoris about 5% or so.

Please refer to FIG. 8A to FIG. 8C, which respectively are the schematicdiagrams of the hard coating layer at some different stages during thecuring process of coating material in accordance with the manufacturingmethod of the polymer plastic front panel of the present invention.After completing the Step 52 (shown in FIG. 6) of applying the liquidcoating material 32 onto the entire bonding surface of the plasticsubstrate 11, the initial status of the plastic substrate 11 will besimilar to the one shown in FIG. 8A that, the coating material 32applied on the bonding surface of the plastic substrate 11 is still in aliquid state, and the thickness of the coating material 32 is relativelythick because the amount of the solvent contained in the coatingmaterial 32 is still large. At this stage, most of the dispersednano-scale flaky inorganic substances 33 contained in the coatingmaterial 32 arc in a non-directional randomly distributed status. Then,as shown in FIG. 8B, when the solvent contained in the coating material32 is gradually evaporated by baking or far-infrared (IR) irradiatingprocess, the coating material will gradually harden and the thicknesswill gradually decrease; therefore, the dispersed nano-scale flakyinorganic substances 33 contained in the coating material 32 will beaffected by the gravity and hydrodynamics, and thus randomly dispersedand arranged along a horizontal direction in a parallel manner withinthe hard coating layer 31. At last, when the curing process iscompleted, as shown in FIG. 8C, the plurality of dispersed nano-scaleflaky inorganic substances 33 will form a discontinuously layereddispersed gas barrier layer in the cured hard coating layer 31. Suchkind of structure of the discontinuously layered dispersed gas barrierlayer not only can provide a good gas barrier effect similar to thecontinuous gas barrier layer shown in FIG. 2 in a crack-free statebecause of its “layered” and “horizontally and parallel dispersed”nano-scale flaky inorganic substances 33; moreover, because thesehorizontally and parallel dispersed nano-scale flaky inorganicsubstances 33 are “discontinuously” layered and stacked, therefore, nocracks will occur in the hard coating layer 31 even after thehigh-temperature, high-temperature and high-humidity, high-lowtemperature (hot and cold) thermal shocks and other harsh automotiveindustry environmental tests are performed. As a result, the polymerplastic front plate 30 made by the manufacturing method of the inventiondescribed above can effectively reduce the diffusion of gas from polymerplastic plates, avoid spilled gas from entering the optical clearadhesive (OCA) layer, solve the problems of bubbles and delaminationafter the environmental tests are performed, and thereby indeedeffectively improve the various shortcomings of the aforementionedconventional techniques.

The applicant has produced several samples of front panels based on thestructures of either the conventional front panels or the inventionshown in FIG. 1 to FIG. 4. Each sample of the front panel is composed ofdifferent resin formulations and solid ingredient ratios and is testedby using the same harsh regulations as the aforementioned automotiveindustry environmental tests. The results of tests are shown in theTable 1 and Table 2 below. Table 1 lists the information of the resinformulations and solid ingredient ratios of a total of twelve samplesincluding sample numbers “Sample1” to “Sample11” and a “ComparativeSample”. Table 2 lists a comparison table of the testing results andperformances of these samples shown in Table 1 after conducting theenvironmental tests.

In the Table 1 below:

the value in the composition column A indicates the weight percentage ofthe organic-inorganic hybrid UV-curable oligomer (including polyurethaneresin and sol-gel silica hybrid mixture) contained in the coatingmaterial of the hard coating layer;

the value in the composition column B indicates the weight percentage ofthe High Tg UV-curable oligomer (e.g., Polyurethane acrylate or High TgUV-curable monomer such as THEICTA) contained in the coating material ofthe hard coating layer;

the value in the composition column C indicates the weight percentage ofthe conventional Spherical Inorganic Nano Gas Barrier Particles (e.g.,Spherical Nano Al₂O₃) contained in the coating material of the hardcoating layer;

the value in the composition column D indicates the weight percentage ofthe Dispersed Nano-scale Flaky Inorganic Substances (e.g., Laminar NanoAl₂O₃) of the invention contained in the coating material of the hardcoating layer;

the value in the composition column E indicates the weight percentage ofthe Photo Initiator contained in the coating material of the hardcoating layer;

the “Comparative Sample” is a sample of front panel formed with a singlecontinuous gas barrier layer on the bonding surface of plastic substrateby a vacuum sputtering process as which shown in FIG. 2.

It can be understood from Table 1 that, because the composition A andcomposition B are the primary materials for the hard coating layer,while the compositions C, D, and E are merely additives; therefore, inpractice, when calculating the solid ingredient ratios contained in theresin formulation of the hard coating layer, the sum of the weightpercentages of the composition A and the composition B (primarymaterials) should be equal to 100%, while the weight percentages of thecompositions C, D, E are considered to be an additional amount ofadditives which is not calculated within the aforementioned 100%.

It can be understood from Table 1 that, except for the “ComparativeSample” which is formed with a single continuous gas barrier layer onthe bonding surface of plastic substrate by a vacuum sputtering processas which shown in FIG. 2; samples of “Sample 1” to “Sample 5” arewithout any gas blocking structure like the conventional technologyshown in FIG. 1; samples of “Sample 6” to “Sample 8” are added withspherical inorganic nano gas barrier particles within the hard coatinglayer like the conventional technology shown in FIG. 3; and, samples of“Sample 9” to “Sample 11” are added with dispersed nano-scale flakyinorganic substances within the hard coating layer like the embodimentof the invention shown in FIG. 4.

TABLE 1 the information of the resin formulations and solid ingredientratios of samples Composition Wt % Sample No A B C D E Remark Sample1100%  — — 5% Sample2 70% 30% — 5% Sample3 60% 40% — 5% Sample4 50% 50% —5% Sample5 40% 60% — 5% Sample6 60% 40%  5% — 5% Sample7 60% 40% 10% —5% Sample8 60% 40% 15% — 5% Sample9 60% 40%  5% 5% Sample10 60% 40% 10%5% Sample11 60% 40% 15% 5% Comparative 100%  5% vacuum sputtering Samplecontinuous gas barrier

TABLE 2 comparison of testing results and performances Item Tested FreeImpact Substrate volume resistance Adhesion porosity Pencil with fallingWater Flexibility Average hardness/ ball (cm)/ boiling/ InkWear-resistance test (R = radius Sample No. 750 g 375 g Initial 12 hrsadhesion of surface 10 mm) R @95 dC Sample 1 5H 30 5B 5B 5B ⊚ X 1.5 nmSample 2 6H 60 5B 5B 5B ⊚ ◯ 1.2 nm Sample 3 5H 100 5B 5B 5B ⊚ ⊚ 1.0 nmSample 4 4H 120 5B 5B 5B ◯ ⊚ 1.0 nm Sample 5 4H 130 5B 5B 5B Δ ⊚ 0.9 nmSample 6 5H 100 5B 5B 5B ⊚ ⊚ 0.9 nm Sample 7 5H 100 5B 5B 5B ⊚ ⊚ 0.9 nmSample 8 5H 60 5B 5B 5B ⊚ ◯ 0.8 nm Sample 9 5H 100 5B 5B 5B ⊚ ⊚ 0.4 nmSample 10 5H 100 5B 5B 5B ⊚ ⊚ 0.3 nm Sample 11 5H 60 5B 5B 5B ⊚ ◯ 0.3 nmComparative 6H <30 5B 5B 5B ⊚ X — Sample Item Tested OCA bonding OCAbonding 85 dC −5% RH OCA bonding −40 dC 95 dC 1000 hrs 1000 hrs OCAbonding −40 100 hrs environmental environmental dC← →85 dC 1000 cyclesSample No. environmental test test test environmental test Sample 1 Δ XX X Sample 2 ⊚ Δ Δ Δ Sample 3 ⊚ Δ Δ Δ Sample 4 ⊚ Δ Δ Δ Sample 5 ⊚ Δ Δ ΔSample 6 ⊚ Δ Δ Δ Sample 7 ⊚ Δ Δ Δ Sample 8 ⊚ Δ Δ Δ Sample 9 ⊚ ◯ ◯ ◯Sample 10 ⊚ ⊚ ⊚ ⊚ Sample 11 ⊚ ⊚ ⊚ ⊚ Comparative Δ Δ Δ Δ Sample Themeaning of symbols shown in Table 2 are described below: ⊚: Excellent,◯: Good, Δ: Normal, X: Fail NG: Not good or ⊚: no bubbles observed, ◯: afew bubbles observed Δ: some big bubbles, X: lamination failure.

The testing methods performed in Table 2 are described below:

1. Pencil hardness test: using Mitsubishi special pencils for hardnesstest, with 750 g loading, performing sliding tests of pencils withdifferent pencil hardness on the surface of the material; if there is noscratch, it is defined as the hardness of the surface (specification: HSK5600).

2. Impact resistance with falling ball: using a 375 g stainless steeliron ball for free falling test to evaluate the height of impactresistance of the material surface (specification: defined byApplicant).

3. Initial adhesion/adhesion after water boiling: removing the 3M tapeafter performing the Cross Cut Test, and then judging the quality ofadhesion according to the surface peeling condition of the material; inaddition, boiling the material with boiling water and then performingthe aforesaid tests to test the adhesion quality after water boiling(specification: ASTM D3002).

4. Wear-resistance of surface: nail scratch resistance under simulateduse of touch panels (specification: defined by Applicant). The meaningsof symbols shown in this column are: ⊚: Excellent (no scratch), ∘: Good(very minor scratches, less than 3 scratches), Δ: Normal (minorscratches, with 3 to 5 scratches), X: Fail (serious scratches, more than5 scratches).

5. Flexibility test: winding the material around a cylinder with aradius of 10 mm and then observing the change of appearance afterflexure (Specification: ASTM D522). The meanings of symbols shown inthis column are: ⊚: Excellent (no scratch), ∘: Good (very minorscratches, less than 3 scratches), Δ: Normal (minor scratches, with 3 to5 scratches),

X: Fail (serious scratches, more than 5 scratches).

6. OCA bonding environmental test: after the material is bonded to thehard coating layer with OCA, performing various environmental tests onit, and then observing whether there are bubbles or delaminationoccurred in the bonding surface after the environmental tests(specification: defined by Applicant). The meanings of symbols shown inthis column are: ⊚: No Bubble Observed, ∘: Few Small Bubbles, Δ: SomeBig Bubbles, X: Lamination Failure.

It can be seen from the above Table 1 and Table 2 that, the samples“Sample9”, “Sample10” and “Sample11” produced according to thetechnology of the present invention have obtained the best test results.It is proved that, the polymer plastic front plate of the invention issuitable for bonding on the surface of automotive touch panels. By meansof the addition of organic-inorganic high Glass Transition Temperature(Tg) UV oligomers and nano-scale flake-like inorganic oxides, a gasbarrier hard coating layer with high surface dyne value (>44 dyne) canbe formed on the adhesion surface of the plastic substrate. It not onlyhas good ink printability and OCA adhesiveness, but also inhibits thediffusion of fugitive gas from polymer plastic front plates duringhigh-temperature, high-temperature and high-humidity, high-lowtemperature (hot and cold) thermal shocks and other harsh automotiveindustry environmental tests, which is due to the fact that thesenano-scale flaky inorganic oxides can form a discontinuously layereddispersed gas barrier layer in the hard coating layer. The gas can beavoided from entering the OCA layer, thereby solving the problems ofbubbles and delamination after the environmental tests are performed.Wherein, the weight percentage of the organic-inorganic hybrid UVoligomer contained in the coating material of the hard coating layer isranged between 50% and 70%, the weight percentage of the high TgUV-curable resin additive is ranged between 30% and 50%, the weightpercentage of the nano-scale flaky inorganic substances in the coatingmaterial of the hard coating layer is between 5% and 15%, and the weightpercentage of the photo initiator is about 5% or so. By using theApplicant's above described polymer material formula, coating materialformula and precision coating technology, the polymer plastic frontplates in accordance with the samples “Sample9”, “Sample10” and“Sample11” can be manufactured for passing the harsh automotive industryenvironmental tests.

While the present invention has been shown and described with referenceto the preferred embodiments thereof and the illustrative drawings, itshould not be considered as limited thereby. Various possiblemodifications and alterations can be conceived by persons skilledwithout departing from the scope and the spirit of the presentinvention.

What is claimed is:
 1. A polymer plastic front plate for bonding on atouch panel, comprising: a plastic substrate, having an operationsurface and a bonding surface; a protective layer, furnished on theoperation surface; and a hard coating layer, furnished on the bondingsurface; characterized by that: said hard coating layer comprising: afirst weight percentage of organic-inorganic hybrid UV-curable oligomer,a second weight percentage of UV-curable resin additives with high glasstransition temperature (Tg) value, a plurality of dispersed nano-scaleflaky inorganic substances, and a photo initiator; wherein, theplurality of dispersed nano-scale flaky inorganic substances arearranged in a randomly distributed horizontal direction in the hardcoating layer to form a discontinuously layered dispersed gas barrierlayer in the hard coating layer.
 2. The polymer plastic front plate ofclaim 1, wherein the organic-inorganic hybrid UV-curable oligomerincludes a polyurethane resin and a sol-gel silica hybrid mixture. 3.The polymer plastic front plate of claim 1, wherein the glass transitiontemperature (Tg) value of the UV-curable resin additives is not lessthan 120° C. ; in addition, the UV-curable resin additives contain atleast one of the following: UV-curable oligomer with high glasstransition temperature (high Tg UV oligomer) and UV-curable monomer withhigh glass transition temperature (high Tg UV monomer).
 4. The polymerplastic front plate of claim 3, wherein the UV-curable oligomer withhigh glass transition temperature is polyurethane acrylate, which has aglass transition temperature (Tg) value not less than 120° C.; inaddition, the UV-curable monomer with high glass transition temperatureis Tris(2-hydroxy ethyl) isocyanuratetriacrylate (THEICTA), which has aglass transition temperature (Tg) value not less than 240° C. .
 5. Thepolymer plastic front plate of claim 1, wherein the nano-scale flakyinorganic substances are composed of at least one of the followingmaterials: SiO₂, Al₂O₃, Si₃N₄, SiO_(x)N_(y), and AlO_(x)N_(y).
 6. Thepolymer plastic front plate of claim 1, wherein each of the nano-scaleflaky inorganic substances has a thickness (t), a longitudinal width(w1) and a lateral width (w2); wherein, the measuring directions of thethickness (t), the longitudinal width (w1) and the lateral width (w2)are perpendicular to each other, and w1 w2 wherein, the thickness (t) isbetween 0.1 nm and 50 nm, the longitudinal width (w1) is between 100 nmand 1000 nm, and the ratio of the lateral width to the longitudinalwidth (w2/w1) is between 0.01 and
 1. 7. The polymer plastic front plateof claim 6, wherein 10 nm≤t≤30 nm, 300 nm≤w1≤800 nm, and 0.1≤(w2/w1)≤1.8. The polymer plastic front plate of claim 1, wherein the value of thefirst weight percentage is ranged between 50% and 70%, the value of thesecond weight percentage is ranged between 30% and 50%, and the value ofthe weight percentage of the nano-scale flaky inorganic substances inthe hard coating layer is between 5% and 15%.
 9. The polymer plasticfront plate of claim 1, wherein the plastic substrate is one of thefollowing: polymethyl methacrylate (PMMA) plate, polycarbonate (PC)plate, PMMA/PC double-layer composite plate, and PMMA/PC/PMMAthree-layer composite plate; in addition, the surface of the hardcoating layer can be applied with an ink layer and an optical clearadhesive (OCA) layer for attaching to the surface of the touch panel.10. A method for manufacturing a polymer plastic front plate,comprising: Step (A): providing a plastic substrate and a coatingmaterial; the plastic substrate having a bonding surface; said coatingmaterial including: a first weight percentage of organic-inorganichybrid UV-curable oligomer, a second weight percentage of UV-curableresin additives with high glass transition temperature (Tg) value, aplurality of dispersed nano-scale flaky inorganic substances, and aphoto initiator; Step (B): applying the coating material onto thebonding surface of the plastic substrate; Step (C): curing the coatingmaterial to form a hard coating layer on the bonding surface of theplastic substrate; wherein, during the curing process, the plurality ofdispersed nano-scale flaky inorganic substances will be affected by thegravity and hydrodynamics, and randomly dispersed and arranged along ahorizontal direction in a parallel manner within the hard coating layer,such that the plurality of dispersed nano-scale flaky inorganicsubstances can form a discontinuously layered dispersed gas barrierlayer in the hard coating layer.
 11. The method for manufacturing apolymer plastic front plate of claim 10, wherein the process forproviding the coating material described in Step (A) comprises thefollowing steps: Step (A1): forming an inorganic layer on a carrierplate; Step (A2): detaching and braking the inorganic layer into aplurality of tiny inorganic fragments; Step (A3): smoothing anddispersing the plurality of tiny inorganic fragments in order totransform the plurality of tiny inorganic fragments into the pluralityof dispersed nano-scale flaky inorganic substances; and Step (A4):adding and mixing the plurality of dispersed nano-scale flaky inorganicsubstances into a solution of the organic-inorganic hybrid UV-curableoligomer, the UV-curable resin additive and the photo initiator to formthe coating material.
 12. The method for manufacturing a polymer plasticfront plate of claim 11, wherein: in Step (A1), the carrier plate is aglass carrier plate, and a release film is provided on a surface of theglass carrier plate; an inorganic material is plated on the release filmby a vacuum sputtering process in order to form a whole piece of theinorganic layer on the surface of the release film; in Step (A2), theinorganic layer is broken by shaking, vibrating or striking the carrierplate, such that the broken inorganic layer can be detached from therelease film of the carrier plate and be broken into the plurality oftiny inorganic fragments; in Step (A3), the plurality of tiny inorganicfragments are mixed and stirred by a nano dispersion equipment, so thatthe plurality of tiny inorganic fragments can collide with each other togradually smooth their sharp edges and also disperse them evenly andindividually, so as to form the plurality of dispersed nano-scale flakyinorganic substances.
 13. The method for manufacturing a polymer plasticfront plate of claim 10, wherein the organic-inorganic hybrid UV-curableoligomer includes a polyurethane resin and a sol-gel silica hybridmixture.
 14. The method for manufacturing a polymer plastic front plateof claim 10, wherein the glass transition temperature (Tg) value of theUV-curable resin additives is not less than 120° C.; in addition, theUV-curable resin additives contain at least one of the following:UV-curable oligomer with high glass transition temperature (high Tg UVoligomer) and UV-curable monomer with high glass transition temperature(high Tg UV monomer).
 15. The method for manufacturing a polymer plasticfront plate of claim 14, wherein the UV-curable oligomer with high glasstransition temperature is polyurethane acrylate, which has a glasstransition temperature (Tg) value not less than 120° C. ; in addition,the UV-curable monomer with high glass transition temperature isTris(2-hydroxy ethyl) isocyanuratetriacrylate (THEICTA), which has aglass transition temperature (Tg) value not less than 240° C.
 16. Themethod for manufacturing a polymer plastic front plate of claim 10,wherein the nano-scale flaky inorganic substances are composed of atleast one of the following materials: SiO₂, Al₂O₃, Si₃N₄, SiO_(x)N_(y),and AlO_(x)N_(y).
 17. The method for manufacturing a polymer plasticfront plate of claim 10, wherein each of the nano-scale flaky inorganicsubstances has a thickness (t), a longitudinal width (w1) and a lateralwidth (w2); wherein, the measuring directions of the thickness (t), thelongitudinal width (w1) and the lateral width (w2) are perpendicular toeach other, and w1≥w2≥t; wherein, the thickness (t) is between 0.1 nmand 50 nm, the longitudinal width (w1) is between 100 nm and 1000 nm,and the ratio of the lateral width to the longitudinal width (w2/w1) isbetween 0.01 and
 1. 18. The method for manufacturing a polymer plasticfront plate of claim 17, wherein 100 nm≤t≤30 nm, 300 nm≤w1≤800 nm, and0.1≤(w2/w1)≤1.
 19. The method for manufacturing a polymer plastic frontplate of claim 10, wherein the value of the first weight percentage isranged between 50% and 70%, the value of the second weight percentage isranged between 30% and 50%, and the value of the weight percentage ofthe nano-scale flaky inorganic substances in the hard coating layer isbetween 5% and 15%.
 20. The method for manufacturing a polymer plasticfront plate of claim 10, wherein the plastic substrate is one of thefollowing: polymethyl methacrylate (PMMA) plate, polycarbonate (PC)plate, PMMA/PC double-layer composite plate, and PMMA/PC/PMMAthree-layer composite plate; in addition, the surface of the hardcoating layer can be applied with an ink layer and an optical clearadhesive (OCA) layer for attaching to the surface of the touch panel.